Vital signs may generally include physiological statistics which indicate basic body functions of a living being. Vital signs are usually measured clinically. However, recent advancement in sensing and computing technology makes biomedical data like heart rate and breathing rate accessible to smartphone users. The monitoring of vital signs has gone beyond the scope of health care to security, sports performance enhancement, leisure, and many others. For example, pulse rate (in beats per minute or bpm) indicates the condition of one person in sports, sleep quality, stress level, and anxiety.
Currently, heart rate monitors may be used to measure pulse rate or pulse rate-derived metrics like heart rate variability (HRV) and blood oxygen saturation (SpO2). Most clinical heart rate monitors like chest straps, Holters, and ECG devices are contact-based measurement devices. They are not designed to be used by multiple users without changing or washing part of or the entirety of the device.
Current video remote heart rate measurement methods and remote photoplethysmograph methods involve taking continuous images and measuring the change in intensity of the subject face or limbs. Some methods require a subject to be still. This is because subject motion will introduce variation of light that is reflected off the surface of the area of interest. This variation of intensity, if falling within the frequency range of the periodic signal of interest to be measured, will decrease the signal-to-noise ratio and skew, affect the robustness, and/or affect the accuracy of the measurement.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one example technology area where some embodiments described herein may be practiced.